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|
-- |
--
-- Message flow
-- Duplex channell
-- This module control /integrity/ of data send and received.
--
--
{-# LANGUAGE DeriveDataTypeable #-}
module Network.BitTorrent.Exchange.Wire
( -- * Wire
Wire
-- ** Exceptions
, ChannelSide (..)
, ProtocolError (..)
, WireFailure (..)
, isWireFailure
, disconnectPeer
-- ** Connection
, Connection
( connCaps, connTopic
, connRemotePeerId, connThisPeerId
)
, getConnection
-- ** Setup
, runWire
, connectWire
, acceptWire
-- ** Query
, getExtCaps
-- ** Messaging
, recvMessage
, sendMessage
, validate
, validateBoth
, trackStats
-- ** Stats
, ConnectionStats (..)
, getStats
, askStats
, recvBytes
, sentBytes
, wastedBytes
, payloadBytes
) where
import Control.Applicative
import Control.Exception
import Control.Monad.Reader
import Data.ByteString as BS
import Data.Conduit
import Data.Conduit.Cereal as S
import Data.Conduit.Network
import Data.Default
import Data.IORef
import Data.Maybe
import Data.Monoid
import Data.Serialize as S
import Data.Typeable
import Network
import Network.Socket
import Network.Socket.ByteString as BS
import Text.PrettyPrint as PP hiding (($$), (<>))
import Text.PrettyPrint.Class
import Data.Torrent.InfoHash
import Network.BitTorrent.Core
import Network.BitTorrent.Exchange.Message
import Data.Torrent
import Data.Torrent.Piece
import Data.BEncode as BE
-- TODO handle port message?
-- TODO handle limits?
-- TODO filter not requested PIECE messages
-- TODO metadata piece request flood protection
-- TODO piece request flood protection
-- TODO protect against flood attacks
{-----------------------------------------------------------------------
-- Exceptions
-----------------------------------------------------------------------}
data ChannelSide
= ThisPeer
| RemotePeer
deriving (Show, Eq, Enum, Bounded)
instance Default ChannelSide where
def = ThisPeer
instance Pretty ChannelSide where
pretty = PP.text . show
-- | Errors occur when a remote peer violates protocol specification.
data ProtocolError
-- | Protocol string should be 'BitTorrent Protocol' but remote
-- peer send a different string.
= InvalidProtocol ProtocolName
| UnexpectedTopic InfoHash -- ^ peer replied with unexpected infohash.
| UnexpectedPeerId PeerId -- ^ peer replied with unexpected peer id.
| UnknownTopic InfoHash -- ^ peer requested unknown torrent.
| HandshakeRefused -- ^ peer do not send an extended handshake back.
| BitfieldAlreadSend ChannelSide
| InvalidMessage -- TODO caps violation
{ violentSender :: ChannelSide -- ^ endpoint sent invalid message
, extensionRequired :: Extension -- ^
}
deriving Show
instance Pretty ProtocolError where
pretty = PP.text . show
-- | Exceptions used to interrupt the current P2P session.
data WireFailure
= PeerDisconnected -- ^ A peer not responding.
| DisconnectPeer -- ^
| ProtocolError ProtocolError
deriving (Show, Typeable)
instance Exception WireFailure
instance Pretty WireFailure where
pretty = PP.text . show
-- | Do nothing with exception, used with 'handle' or 'try'.
isWireFailure :: Monad m => WireFailure -> m ()
isWireFailure _ = return ()
{-----------------------------------------------------------------------
-- Stats
-----------------------------------------------------------------------}
data FlowStats = FlowStats
{ messageBytes :: {-# UNPACK #-} !ByteStats
, messageCount :: {-# UNPACK #-} !Int
-- msgTypes :: Map MessageType Int
} deriving Show
-- | Note that this is stats is completely different from Progress:
-- TODO explain why.
data ConnectionStats = ConnectionStats
{ incomingFlow :: !ByteStats
, outcomingFlow :: !ByteStats
} deriving Show
instance Default ConnectionStats where
def = ConnectionStats def def
addStats :: ChannelSide -> ByteStats -> ConnectionStats -> ConnectionStats
addStats ThisPeer x s = s { outcomingFlow = outcomingFlow s <> x }
addStats RemotePeer x s = s { incomingFlow = incomingFlow s <> x }
recvBytes :: ConnectionStats -> Int
recvBytes = byteLength . incomingFlow
sentBytes :: ConnectionStats -> Int
sentBytes = byteLength . outcomingFlow
wastedBytes :: ConnectionStats -> Int
wastedBytes (ConnectionStats _in out) = overhead _in + overhead out
payloadBytes :: ConnectionStats -> Int
payloadBytes (ConnectionStats _in out) = payload _in + payload out
{-----------------------------------------------------------------------
-- Connection
-----------------------------------------------------------------------}
data Connection = Connection
{ connCaps :: !Caps
, connTopic :: !InfoHash
, connRemotePeerId :: !PeerId
, connThisPeerId :: !PeerId
, connStats :: !(IORef ConnectionStats)
, connExtCaps :: !(IORef ExtendedCaps)
}
instance Pretty Connection where
pretty Connection {..} = "Connection"
isAllowed :: Connection -> Message -> Bool
isAllowed Connection {..} msg
| Just ext <- requires msg = ext `allowed` connCaps
| otherwise = True
{-----------------------------------------------------------------------
-- Hanshaking
-----------------------------------------------------------------------}
sendHandshake :: Socket -> Handshake -> IO ()
sendHandshake sock hs = sendAll sock (S.encode hs)
-- TODO drop connection if protocol string do not match
recvHandshake :: Socket -> IO Handshake
recvHandshake sock = do
header <- BS.recv sock 1
unless (BS.length header == 1) $
throw $ userError "Unable to receive handshake header."
let protocolLen = BS.head header
let restLen = handshakeSize protocolLen - 1
body <- BS.recv sock restLen
let resp = BS.cons protocolLen body
either (throwIO . userError) return $ S.decode resp
-- | Handshaking with a peer specified by the second argument.
--
-- It's important to send handshake first because /accepting/ peer
-- do not know handshake topic and will wait until /connecting/ peer
-- will send handshake.
--
initiateHandshake :: Socket -> Handshake -> IO Handshake
initiateHandshake sock hs = do
sendHandshake sock hs
recvHandshake sock
-- | Tries to connect to peer using reasonable default parameters.
connectToPeer :: PeerAddr -> IO Socket
connectToPeer p = do
sock <- socket AF_INET Stream Network.Socket.defaultProtocol
connect sock (peerSockAddr p)
return sock
{-----------------------------------------------------------------------
-- Wire
-----------------------------------------------------------------------}
type Wire = ConduitM Message Message (ReaderT Connection IO)
protocolError :: ProtocolError -> Wire a
protocolError = monadThrow . ProtocolError
disconnectPeer :: Wire a
disconnectPeer = monadThrow DisconnectPeer
readRef :: (Connection -> IORef a) -> Wire a
readRef f = do
ref <- lift (asks f)
liftIO (readIORef ref)
writeRef :: (Connection -> IORef a) -> a -> Wire ()
writeRef f v = do
ref <- lift (asks f)
liftIO (writeIORef ref v)
modifyRef :: (Connection -> IORef a) -> (a -> a) -> Wire ()
modifyRef f m = do
ref <- lift (asks f)
liftIO (atomicModifyIORef' ref (\x -> (m x, ())))
getExtCaps :: Wire ExtendedCaps
getExtCaps = readRef connExtCaps
setExtCaps :: ExtendedCaps -> Wire ()
setExtCaps = writeRef connExtCaps
getStats :: Wire ConnectionStats
getStats = readRef connStats
askStats :: (ConnectionStats -> a) -> Wire a
askStats f = f <$> getStats
putStats :: ChannelSide -> Message -> Wire ()
putStats side msg = modifyRef connStats (addStats side (stats msg))
getConnection :: Wire Connection
getConnection = lift ask
validate :: ChannelSide -> Wire ()
validate side = await >>= maybe (return ()) yieldCheck
where
yieldCheck msg = do
caps <- lift $ asks connCaps
case requires msg of
Nothing -> return ()
Just ext
| ext `allowed` caps -> yield msg
| otherwise -> protocolError $ InvalidMessage side ext
validateBoth :: Wire () -> Wire ()
validateBoth action = do
validate RemotePeer
action
validate ThisPeer
trackStats :: Wire ()
trackStats = do
mmsg <- await
case mmsg of
Nothing -> return ()
Just msg -> putStats ThisPeer msg -- FIXME not really ThisPeer
runWire :: Wire () -> Socket -> Connection -> IO ()
runWire action sock = runReaderT $
sourceSocket sock $=
S.conduitGet S.get $=
action $=
S.conduitPut S.put $$
sinkSocket sock
sendMessage :: PeerMessage msg => msg -> Wire ()
sendMessage msg = do
ecaps <- getExtCaps
yield $ envelop ecaps msg
recvMessage :: Wire Message
recvMessage = await >>= maybe (monadThrow PeerDisconnected) return
extendedHandshake :: ExtendedCaps -> Wire ()
extendedHandshake caps = do
sendMessage $ nullExtendedHandshake caps
msg <- recvMessage
case msg of
Extended (EHandshake ExtendedHandshake {..}) -> do
setExtCaps $ ehsCaps <> caps
_ -> protocolError HandshakeRefused
connectWire :: Handshake -> PeerAddr -> ExtendedCaps -> Wire () -> IO ()
connectWire hs addr extCaps wire =
bracket (connectToPeer addr) close $ \ sock -> do
hs' <- initiateHandshake sock hs
unless (def == hsProtocol hs') $ do
throwIO $ ProtocolError $ InvalidProtocol (hsProtocol hs')
unless (hsInfoHash hs == hsInfoHash hs') $ do
throwIO $ ProtocolError $ UnexpectedTopic (hsInfoHash hs')
unless (hsPeerId hs' == fromMaybe (hsPeerId hs') (peerId addr)) $ do
throwIO $ ProtocolError $ UnexpectedPeerId (hsPeerId hs')
let caps = hsReserved hs <> hsReserved hs'
let wire' = if ExtExtended `allowed` caps
then extendedHandshake extCaps >> wire
else wire
extCapsRef <- newIORef def
statsRef <- newIORef def
runWire wire' sock $ Connection
{ connCaps = caps
, connTopic = hsInfoHash hs
, connRemotePeerId = hsPeerId hs'
, connThisPeerId = hsPeerId hs
, connExtCaps = extCapsRef
, connStats = statsRef
}
acceptWire :: Wire () -> Socket -> IO ()
acceptWire = undefined
|